Amide Functionalizing tfz Topological Co 6 (μ 3 -OH) 6 -MOF for One-Step MTO Products Separation

The separation of methanol-to-olefin (MTO) products to obtain high-purity ethylene (C 2 H 4 ) and propylene (C 3 H 6 ) is critical. However, developing adsorbents with high adsorption capacity and selectivity for C 2 H 4 /C 3 H 6 remains highly challenging, due to their similar physicochemical properties. Herein, a stable amide-functionalized and tfz topological metal–organic framework (MOF), [Co 6 (OH) 6 (NTB) 2 (NPI) 3 ]· x guest (NJTU-Bai87, NJTU-Bai = Nanjing Tech University Bai’s group), was synthesized through mixed ligands of 4,4′,4″-nitrilotribenzoic acid (H 3 NTB) and N -(pyridin-4-yl)isonicotinamide (NPI), which exhibits both excellent uptake capacities of C 3 H 6 (200.9 cm 3 g –1 ) and C 2 H 6 (78.2 cm 3 g –1 ) and high selectivities for equimolar mixtures of C 3 H 6 /C 2 H 4 (10.5) and C 2 H 6 /C 2 H 4 (1.45) at 298 K and 1 bar, respectively. Furthermore, breakthrough experiments demonstrate that the NJTU-Bai87 could achieve one-step acquisition of polymer-grade C 2 H 4 (≥99.9%) during C 3 H 6 /C 2 H 4 and C 2 H 6 /C 2 H 4 separation. Very interestingly, for C 3 H 6 /C 2 H 4 mixture (50/50, v/v), high-purity C 2 H 4 (≥99.9%) and C 3 H 6 (≥99.5%) can be directly harvested or recovered upon desorption, with ultrahigh productivities of 160 and 73.8 L kg –1, respectively, which surpass many well-developed MOFs for C 3 H 6 /C 2 H 4 separation. This work may provide valuable insights for the rational design of high-performance MOFs for practical C 2 H 4 purification.